Diagnostic Instructions
Circuit/System Description
This Engine Cranks but Does Not Run diagnostic is an organized approach to identify a condition which causes the engine to crank but does not continue to run. This diagnostic directs the service technician to the appropriate system diagnosis. This diagnostic
assumes the vehicle system voltage levels are adequate for starter motor operation. Refer to
Battery Inspection/Test and
Engine Cranks Slowly. The fuel level supply must be adequate,
and the fuel quality must be able to sustain the combustion process.
Diagnostic Aids
• | When disconnecting electrical connectors or removing fuses and relays from a fuse block, always inspect both mating electrical terminals for corrosion and terminal tightness. |
• | Use the
J 35616
Connector Test Adapter Kit for any test that requires probing the underhood fuse block terminals, component wire harness terminals, or the ECM wire harness terminals. |
Reference Information
Schematic Reference
Engine Controls Schematics
Connector End View Reference
Component Connector End Views
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Special Tools
Circuit/System Verification
Attempt to start the engine. The engine should start and run.
Circuit/System Testing
- Ignition OFF, open the hood to disable the Auto Stop function. Refer to
Hybrid Modes of Operation Description.
- Ignition ON, verify the scan tool hood position parameter displays Open.
- Crank the engine for 15 seconds.
- Observe the vehicle DTC information with a scan tool.
- With the ignition ON and the engine OFF, test the fuses that are supplied ignition 1 voltage by the powertrain relay. The test lamp should illuminate ON for each test point of the fuses.
⇒ | If the test lamp does not illuminate ON for at least one test point of each fuse, refer to
DTC P0685 or P0690. |
- Crank the engine for 15 seconds. Observe the engine speed parameter with a scan tool.
⇒ | If engine RPM is not indicated, refer to
DTC P0335. |
- Install a spark plug tester onto one ignition module/coil assembly on each bank of the engine.
- Observe both spark plug testers.
Important: An erratic or weak spark is considered a no spark condition.
- Crank the engine for 15 seconds. The ignition coil secondary voltage should be observed across the gap of both spark plug testers.
- With the ignition ON and the engine OFF, command the fuel pump ON and OFF with the scan tool. The fuel pump should energize when commanded ON, and de-energize when commanded OFF.
- Turn OFF the ignition.
- Install the
J 34730-1A
Fuel Pressure Gage. With the ignition ON and the engine OFF, command the fuel pump ON several times with the scan tool. Refer to
Fuel System Diagnosis for the fuel pressure specification.
- Inspect for the following conditions:
• | Compare the actual engine coolant temperature to the ECT parameter. |
• | Filter and air intake system for restrictions and obstructions |
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic procedure.